Apparatus for dressing a helically ribbed grinding wheel

ABSTRACT

Apparatus for dressing a helically ribbed grinding wheel is disclosed in which head is provided for traversing movement parallel with the grinding wheel axis for traversing a pair of dressing tools across the rib form of the grinding wheel, the dressing tools being carried by corresponding mutually inclined tool slides in turn carried by carrier slides which latter are slidable relative to one another on the head in a direction parallel with the grinding wheel axis whilst the head carries actuating means or slides operable or indexible in conjunction with traverse of the head for imparting incremental feeding movement to the tool slides prior to an operative traverse and through a coacting member or rocker to each tool slide, the actuating means or slides having a sliding cooperation with the coacting members or rockers in a direction parallel with the grinding wheel axis in order to permit relative movement of the carrier slides independently of the dressing tool feeding movement i.e. for the purpose of enabling the dressing tools to be moved towards one another for return traverse or for imparting fine movement to the dressing tools in effecting variation in the grinding wheel rib flank form dressed thereby.

United States Patent [72] Inventors Thomas Meyrick Deakin f Attrney-Watson, Cole, Grindle & Watson Victor A. G. Cooper, Coventry, England Appl. No, 742,048 Filed July 2, 1968 ABSTRACT: Apparatus for dressing a helically ribbed grind- Patented Mar. 9, 1971 ing wheel is disclosed in which head is provided for traversing Assignee Coventry Gauge & T l Company Li i d movement parallel with the grinding wheel axis for traversing Coventry, England a pair of dressing tools across the rib form of the grinding wheel, the dressing tools being carried by corresponding mutually inclined tool slides in turn carried by carrier slides which latter are slidable relative to one another on the head in a direction parallel with the grinding wheel axis whilst the APPARATU FOR DRESSING A HELICALLY head carries actuating means or slides operable or indexible in RIBBED GRINDIN WHEEL conjunction with traverse of the head for imparting incremen- Cl i 5 D i Figs tal feeding movement to the tool slides prior to an operative U traverse and through a coacting member or rocker to each .S. C.- tool lide the actuating means or slides havin a slidin r t Cl g g 53/00 cooperation with the coacting members or rockers in a m d Search 1 direction arallel the grinding wheel axis in order to per- References Cited mit relatiye movement of the carrier slides independently of the dressing tool feeding movement 1.e. for the purpose of UNITED STATES PATENTS enabling the dressing tools to be moved towards one another 2,907,314 /1959 Osplack 125/11 for return traverse or for imparting fine movement to the 2,792,824 5/1957 Ricltenmann 125/11 dressing tools in effecting variation in the grinding wheel rib l/ 1940 Schrcht 125/1 1 flank form dressed thereby.

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saw u 0F 5 I NNNNNN as Tnmvms Mmmcuc Damnwu Vuc'rma ARTHUR GORDON COOPER ATTORNEY AEWARATEE 1. 6m DIRESSHNG A HELiCAlLLY RlBBED GRHNDHNG WHEEL This invention relates to the dressing or trueing of helically ribbed grinding wheels e.g. as used for gear or screw thread grinding and has for its object to provide improved apparatus for dressing such wheels to a high degree of accuracy as regards wheel rib form and also for obtaining desired variation in the latter whilst other practical advantages will be apparent from the following disclosure.

in a practical embodiment of the invention it is hereafter described as applied to the dressing of a helically ribbed gear grinding wheel, reference being made to the accompanying drawings in which:

MG. 1 is a front elevation of the head of grinding wheel dressing apparatus according to this invention,

FIG. 2 is a plan view including the mounting of the head,

PEG. 3 is an end view in the direction of the arrow 11 of FIG.

F165. 4 and 5 are a detail plan view and axial plane section respectively of means for modifying lead screw traverse of the head.

Referring to the drawings the head 1 of the dresser carrying a pair of diamond dressing tools 2, 2 and slide and operating mechanism for the latter, is shown arranged in an overhead position in relation to the grinding wheel 3 rotatable about a horizontal axis for grinding a gear wheel or a stack of the latter rotatable about a vertical axis in the machine. However it is to be understood that the head 1 is capable of other similar generally radial relationship to a grinding wheel 3 such as in a horizontal or inclined plane.

The dresser head i is mounted for vertical adjusting movement indicated at 4 for readily advancing it to an operative dressing position or retracting it therefrom and also for enabling it to assume an appropriate operative position having regard to reduction in the diameter of the wheel 3 due to wear. However once the dresser head 1 is set by such vertical adjustment in an operative position it is locked or held thereat during a dressing operation so that error due to vertical movement of the head 1 during dressing is avoided.

For such vertical adjusting movement the dresser head 1 is mounted from a support member 41 vertically adjustable in a carriage 42 by hydraulic piston and cylinder means 43 provided in the carriage 452, which means 43 is shown including provision for screw operation of the support member 41 relative to the piston at 4-3 by a screw 44 arranged for manual operation by a hand wheel 45 at the top of the carriage 62.

Control of the double acting hydraulic piston and cylinder means 43 is by suitable solenoid operated valve means (not shown) in the hydraulic fluid supply to it, which control valve means is in turn controlled by limit switches for determining the upward and downward extent of movement of the carriage 42 in relation to the grinding wheel 3.

The carriage 42 is mounted by roller slide means 46 on a base member 47 which is fixed in relation to the grinding machine or may form part of the latter, so that the carriage 4-2 and dresser head 1 carried thereby can be traversed horizon tally in relation to the grinding wheel 3 by lead screw or lead bar 27 carried by the base member 67 and cooperating with a nut 28 on the carriage 42, which lead screw 27 is driven in timed relationship with rotation of the grinding wheel 3 by an appropriate train of change gears 29 from the latter.

Each dressing tool 2 is carried by a corresponding slide 6, the pair of slides 6,6 being mutually inclined for required movement having regard to the flank angle of the wheel rib form 3a, slideway members 7,7 for said slides 6,6 being carried by carrier slides 9,9 horizontally slidable on slideway 9a of the dresser head 1 for purposes referred to hereafter. Apart from provision for adjustable setting at 8, the slideway members 7,7 are bolted fast to their respective horizontal slides 9,9.

The dresser head 1 also carries a pair of vertically movable actuating slides 10,11) operated by corresponding screws 11,11 which are driven in unison by pulleys 12,12 arranged to be positively driven by a toothed belt 13. Each vertical slide 10 is provided with a horizontal surface 14 at right angles to its sliding movement and arranged to slidably contact an end or nose 15a of an arm 15 of a rocker 16 pivoted at 16a on the corresponding member 7, the end or nose 17a of the other or shorter arm 17 of the rocker 16 contacting the head of an adjustment screw 19 carried on the tool slide 6.

The tool slides 6,6 are spring loaded such as by tension springs 18,18 anchored between them and their corresponding slideway members 7,7 for maintaining the slides 6,6 or their adjusting screws 19,19 in intimate contact with corresponding rocker arms 17,17 and also the longer arms 15,15 of the latter in similar contact with the surfaces 14,16 of the vertical slides 10,10.

It will therefore be appreciated that as upward movement of the vertical slides 10,10 proceeds the rockers 16,16 actuate their corresponding tool slides 6,6 for feeding the dressing tools 2,2 radially towards the wheel 3, whilst as the dresser head 1 is traversed horizontally the dressing tools 2,2 move across the helical rib form 3a of the wheel 3 in timed relationship with rotation of the latter such that the tools 2,2 enter between adjacent rib flanks.

The arrangement is preferably such that in one direction of traversing movement (e.g. from left to right) the tips or diamonds 2a, 2a of the dressing tools 2,2 are in dressing contact with corresponding flanks of the wheel rib form 3a but that on return traverse the tools 2,2 are slightly moved towards one another so that they clear the rib flanks as they pass back across the wheel rib form 3a. However if desired the tools 2,2 may also effect dressing during a return traverse.

The required extent of traversing movement of the carriage 42 and head 1 is controlled by limit switches (one of which is shown at 43 in FIG. 3) which in turn control the drive to the grinding wheel 3 for dressing purposes, rotation of the wheel 3 being reversed for a return traverse of the dressing tools 2,2.

Prior to commencement of a further operative traverse with the tools 2,2 in dressing contact with the rib flanks, the tools 2,2 are subject to an incremental feed by the vertical slide and rocker mechanism 10, 16 already referred to.

In order to operate the vertical slides 10,111 for such incremental feed a slide 20 slidable on the dresser head 1 between the runs of the driving belt 13 is arranged for two-way operation by a double acting hydraulic piston and cylinder 21 also carried by the dresser head 1 between the belt runs, which slide 20 carries a spring loaded pawl 22 arranged to engage the teeth 13a on the inside face of one of the belt runs. Thus as the slide 20 is hydraulically actuated for back and forth movement the belt 13 is intermittently advanced unidirectionally for correspondingly driving the pulleys 12, 12 and screws 11,11 and hence imparting incremental upward vertical movement to the slides 10, 10.

Accurate fine movement of the dressing tools 2,2 is obtained per feed from the coarse step operation of the belt 13 by the pawl slide 20 firstly due to the screw operation of the vertical slides 10,10 and secondly due to the fact that magnified movement of the slides 10,10 imparts reduced movement to the tool slides 6,6 owing to the relative lengths of the rocker arms 15,17. Such reduction ratio may be of the order of 4:1 as shown but may be varied according to requirements.

The extent of movement of the slide 20 is controlled by limit switches 50,51 on the head 1 (FIG. 2) cooperating with adjustable stops 52,53 on the slide 20 which limit switches 50,51 control solenoid operated valve means in the hydraulic fluid supply to the hydraulic piston and cylinder 21.

For the purpose of return traverse of the tools 2,2 clear of the rib flanks, the tools are brought towards one another for a slight extent by corresponding movement of the horizontal slides 9,9 which are operated by the hydraulic piston and cylinder arrangement 23 of which the cylinder 23a is carried by one slide (viz the left hand slide) and the piston 23b is connected to the other slide of the horizontal slides 9,9. This piston and cylinder 23 is hydraulically operated in timed relationship with the piston and cylinder 21. operating the pawl slide 26! as indicated by the hydraulic'pipe work connection 55.

Owing to the sliding cooperation of the nose 15a of the arm 15 of each rocker 16 with the horizontal surface 14 of the corresponding actuating slide 10, relative sliding movement of the horizontal slides 9,9 can take place independently of incremental feeding movement imparted to the tool slides 6,6 by the actuating slides 10,10.

At the commencement of a dressing operation the vertical slides 10,10 are in a lower position but progressively advance up the dresser head 1 to in turn feed the dressing tools 2,2 radially inwards in relation to the wheel. On completion of a full dressing operation ie for the full extent of the rib flanks a stop 24 on one of the vertical slides contacts a switch 25 for stopping the operation of the dresser prior to upward retraction of the head 1 from the wheel 3. One or both of the screws 11,11 is arranged to receive a handle at 26 for rotating both of the screws 11,11 through the belt drive 13 to return the vertical slides 10,10 to their lower position in readiness for a further dressing operation.

In accordance with a further feature of this invention for enabling desired variation, correction or relief of the form being dressed on the rib flanks, provision is included on the dresser head 1 for imparting very fine lateral movement to the tools 2,2 during dressing i.e. in a direction parallel to the axis of the grinding wheel 3.

For this purpose each vertical slide 10 is shown provided with a member or plate 30 formed with a cam surface or edge 31 which cooperates with an end or nose 32a of a corresponding upright lever 32 pivotally mounted at 33 at its lower end on the head 1, the lever 32 being urged by a tension spring 34 to maintain contact with the cam surface 31. Rotationally fast with each lever 32 is an eccentric pin 35 cooperating with a follower 36 carried by the corresponding horizontal slide 9.

As the vertical slides 10,10 progressively advance upwards in effecting incremental feed of the dressing tools 2,2 as already described, it will be appreciated that each lever 32 cooperates with its corresponding cam surface 31 to impart fine horizontal movement to the horizontal slides 9,9 and hence corresponding lateral movement to the tools 2,2 for modifying the rib flank form dressed thereby as their incremental feed proceeds.

Although in one sense the fine adjustment cam and lever mechanism 31,32 operates in conjunction with the incremental feed for obtaining a required dressed form by the tools 2,2 in another sense it operates independently of such feed since the increments of radial tool feed into the wheel 3 remain constant and of uniformly equal amounts despite the fine adjustment effected. This is due to the fact that the fine adjustment of the horizontal slides 9,9 by the cam and lever mechanism 31,32 is at right angles to the movement of the vertical slides 10,10 and that in particular the operation of the rockers 16,16 by the horizontal surfaces 14,14 of the vertical slides 10,10 is unaffected by the fine horizontal adjustment which is accommodated by sliding movement of the rockers 16,16 laterally relative to said surfaces 14,14.

As shown in regard to the right hand horizontal slide 9 the follower 36 is carried for horizontal adjustment relative thereto by the screw means 37 and after such adjustment is positively locked by the clamping screws 38 and pad 39 thus avoiding any relative play which would otherwise impair the fine adjustment afforded by the cam and lever mechanism 31,32. Such adjustment can be ofa very fine degree having regard to the cam form at 31 and in particular the effective length of the lever 32 in relation to the throw of the eccentric pin 35 which as shown gives a reduction of the order of 40:1 but which may be varied according to requirements. The resulting magnified form of each cam surface 31 is such that its shaping is facilitated for obtaining the required high degree of fine adjustment.

As well as cooperating with the follower 36 for imparting fine adjustment to the corresponding horizontal slide 9 during dressing contact of the tools 2,2 with the wheel rib form 3a the cooperation of the eccentric pin 35 with the follower 36 is also such as to allow some relative movement of the follower 36 and pin 35 for permitting movement of the horizontal slides 9,9 towards one another under the action of the cylinder and piston 23 for return traverse of the tools 2,2 clear of the wheel rib form 3a in readiness for an operative traverse. For this purpose the pin 35 is shown operating between opposed side faces 40a, 40b of a transverse slot 40 in its corresponding follower 36, the pin 35 bearing against the left hand face 40a when fine adjustment is being effected during dressing, whilst some clearance is left between the pin 35 and the other face 40b to permit movement together of the slides 9,9 for return traverse.

Referring to F165. 2 to 5 provision is shown included at 60 for modifying the traverse of the head 1 for setting or finally setting the operation of the dresser for the required pitch of the wheel rib form 3a being dressed. Whereas this is achieved as closely as possible by selection of appropriate change gears 29 in the gear train to the lead screw 27, final modified traverse movement of the head 1 may be obtained by advancing or retarding the lead screw in its operation of the carriage 42 and head 1. For this purpose a linear cam provided by a sine bar 62 carried by a bracket 63 extending from one end of the carriage 42, cooperates with a follower 64 carried by a slide 65 slidably mounted on the base member 47, which follower 64 is fixed in relation to the slide 65 apart from the provision for screw adjustment at 66. i

The slide 65 is secured at 65a to one'end of a flexible band 67 passing about a rotatable member 69 of lead screw actuating mechanism 70 which band 67 is anchored by tension springing 71 to a fixed bracket 72 extending rearwardly from the base member 47 whereby the band 67 has a spring loaded action on the slide 65 in maintaining the follower 64 against the sine bar 62.

As the carriage 42 and head 1 are traversed horizontally by normal rotary action of the lead screw 27, the follower 64 cooperates with the edge 61 of the sine bar 62 and resulting movement of the slide 65 and band 67 causes angular movement of the rotatable member 69 to which the band 67 is secured at 68.

The rotary member 69 is rotationally fast with a sleeve 74 (FIG. 5) located between thrust bearings 75,75 on the lead screw 27 which sleeve 74 has a threaded engagement 76 with a nut assembly 77 fixed to the adjacent end of the base member 47, which threaded engagement 76 is shown of the recirculating ball type for suitable accuracy. Thus on angular movement being imparted to the rotatable member the screw engagement 76 of the sleeve 74 with the fixed nut assembly 77 is such that axial movement is imparted to the sleeve 74 and hence corresponding axial movement to the lead screw 27 for obtaining required modification of the traverse of the carriage 42 and head 1 as provided by the normal rotary action of the lead screw 27 such superimposed modification or axial movement of the lead screw 27 can be effected to a fine degree by appropriate slip gauge setting of the sine bar 62 at 79.

Whereas a practical embodiment of the invention has now been described with reference to the accompanying drawings, it is to be understood that details of construction and operation may be modified within the scope of the invention as now claimed.

We claim:

1. Apparatus for dressing a helically ribbed grinding wheel comprising a head arranged to be traversed parallel with the axis of the grinding wheel and in timed relationship with rotation of the latter; a pair of carrier slides slidably carried by said head for movement relative to one another in a direction parallel to the grinding wheel axis; a tool slide slidably carried by each carrier slide for feeding movement towards the grinding wheel axis, the directions of sliding feed movement of the pair of tool slides being mutually inclined generally according to rib flank angle of the grinding wheel; a dressing tool carried by each tool slide whereby the pair of dressing tools enter between the flanks of the wheel rib form for dressing contact with corresponding wheel rib flanks during an operative traverse of the head in at least one direction of traversing movement thereof; actuating means carried by said head and operable in conjunction with traversing movement of the latter for imparting incremental feeding movement to the tool slides and dressing tools carried thereby prior to an operative traverse of the head, said actuating means having a sliding cooperation with a coacting member to each tool slide in a direction parallel to the grinding whee l axis whereby any movement of the carrier slides relative to one another in a direction parallel to the grinding wheel axis is independent of said incremental feeding'movement by virtue of said sliding cooperation. Y

2. Apparatus according to claim 1 wherein the actuating means consists of a pair of actuating slides operatively movable together in a direction away from the grinding wheel axis, each said actuating slide having a surface parallel with the grinding wheel axis and cooperating with an arm of a coacting rocker member to a corresponding tool slide which rocker member is pivotally carried by the corresponding carrier slide, a further arm of the rocker member acting upon said corresponding tool slide for imparting feeding movement thereto, and means operating in conjunction with the traversing movement of the head for indexing the actuating slides for said operative movement in order to impart said incremental feeding movement to the tool slides and dressing tools carried thereby via the rocker members and independently of any movement of the carrier slides relative to one another in a direction parallel to the grinding wheel axis by virtue of the means and arranged to operate the carrier slides for sliding movement towards one another in a direction parallel with the axis of the grinding wheel for in turn effecting movement of the dressing tools towards one another for return traverse of the latter by the head and between the grinding wheel rib flanks but clear of contact with the latter and on reverse rotation of the grinding wheel.

4. Apparatus according to claim 1 wherein cam means carried by the actuating means cooperates with follower means on the carrier slides for imparting sliding movement thereto in a direction parallel with the axis of the grinding wheel in order to impart corresponding movement to the tool slides and dressing tools carried thereby during incremental feeding movement thereof by the actuating means and for the purpose of effecting variation in the grinding wheel rib flank form dressed by the dressing tools.

5. Apparatus according to claim 2 wherein each actuating slide is provided with a cam cooperating with a corresponding lever pivoted on the head, which lever in turn cooperates with a follower carried by the corresponding carrier slide for imparting sliding movement thereto in a direction parallel with the grinding wheel axis in order to impart corresponding movement to the associated tool slideand dressing tool carried thereby during incremental feeding movement thereof by said actuating slide, the movement imparted to each dressing tool in this way effecting variation inthe grinding wheel rib flank form dressed by the dressing tools. 

1. Apparatus for dressing a helically ribbed grinding wheel comprising a head arranged to be traversed parallel with the axis of the grinding wheel and in timed relationship with rotation of the latter; a pair of carrier slides slidably carried by said head for movement relative to one another in a direction parallel to the grinding wheel axis; a tool slide slidably carried by each carrier slide for feeding movement towards the grinding wheel axis, the directions of sliding feed movement of the pair of tool slides being mutually inclined generally according to rib flank angle of the grinding wheel; a dressing tool carried by each tool slide whereby the pair of dressing tools enter between the flanks of the wheel rib form for dressing contact with corresponding wheel rib flanks during an operative traverse of the head in at least one direction of traversing movement thereof; actuating means carried by said head and operable in conjunction with traversing movement of the latter for imparting incremental feeding movement to the tool slides and dressing tools carried thereby prior to an operative traverse of the head, said actuating means having a sliding cooperation with a coacting member to each tool slide in a direction parallel to the grinding wheel axis whereby any movement of the carrier slides relative to one another in a direction parallel to the grinding wheel axis is independent of said incremental feeding movement by virtue of said sliding cooperation.
 2. Apparatus according to claim 1 wherein the actuating means consists of a pair of actuating slides operatively movable together in a direction away from the grinding wheel axis, each said actuating slide having a surface parallel with the grinding wheel axis and cooperating with an arm of a coacting rocker member to a corresponding tool slide which rocker member is pivotally carried by the corresponding carrier slide, a further arm of the rocker member acting upon said corresponding tool slide for imparting feeding movement thereto, and means operating in conjunction with the traversing movement of the head for indexing the actuating slides for said operative movement in order to imPart said incremental feeding movement to the tool slides and dressing tools carried thereby via the rocker members and independently of any movement of the carrier slides relative to one another in a direction parallel to the grinding wheel axis by virtue of the parallel surfaces of said actuating slides cooperating with the associated arms of the rocker members.
 3. Apparatus according to claim 1 wherein operating means is provided operable in timed relationship with the actuating means and arranged to operate the carrier slides for sliding movement towards one another in a direction parallel with the axis of the grinding wheel for in turn effecting movement of the dressing tools towards one another for return traverse of the latter by the head and between the grinding wheel rib flanks but clear of contact with the latter and on reverse rotation of the grinding wheel.
 4. Apparatus according to claim 1 wherein cam means carried by the actuating means cooperates with follower means on the carrier slides for imparting sliding movement thereto in a direction parallel with the axis of the grinding wheel in order to impart corresponding movement to the tool slides and dressing tools carried thereby during incremental feeding movement thereof by the actuating means and for the purpose of effecting variation in the grinding wheel rib flank form dressed by the dressing tools.
 5. Apparatus according to claim 2 wherein each actuating slide is provided with a cam cooperating with a corresponding lever pivoted on the head, which lever in turn cooperates with a follower carried by the corresponding carrier slide for imparting sliding movement thereto in a direction parallel with the grinding wheel axis in order to impart corresponding movement to the associated tool slide and dressing tool carried thereby during incremental feeding movement thereof by said actuating slide, the movement imparted to each dressing tool in this way effecting variation in the grinding wheel rib flank form dressed by the dressing tools. 